Over the years, the disposition of discarded tires has progressively become a serious environmental problem. With increasing numbers of vehicles being employed worldwide, the number of tires discarded annually has increased correspondingly. The quantity of discarded tires continues to grow despite efforts of tire manufacturers to extend the operating life of tires and efforts of retreaders to retread tires, particularly truck tires, as many times as possible, until such time as the carcass is damaged or worn to such an extent that retreading to produce a safe tire is no longer feasible.
For many years, tires were conventionally discarded into landfills along with other trash. This did not prove to be a satisfactory solution due to the relatively large volume of a tire, the number of discarded tires, and the fact that vulcanized rubber degrades little, if at all, even over time periods of many years. Thus, the disposal of scrap tires by dumping into landfills has been recognized for some years as a long-term unsatisfactory solution.
As a means of limiting the number of discarded tires deposited in landfills, efforts have been made for a number of years to devise commercial usages for discarded tires. In this respect, there have been proposals for the usage of discarded tires as resilient barriers protecting bridge abutments along roadways and other similar applications. Another proposed usage for discarded tires has involved ocean dumping to a create reef-like habitat for fish. These proposed commercial usages, while proving to be operationally feasible, do not make possible the usage of any significant quantities of scrap tires in the context of the many millions of tires which are necessarily discarded on an annual basis.
Efforts have been made for a number of years to effect a thermal decomposition of the rubber in tires for purposes of either reusing the rubber or to make use of the heat output while destroying the tire such that it does not constitute an environmental problem. While significant heat energy as for electrical power generation or other heating applications can be derived from burning tires, there have been problems associated with the burning of tires which involve the handling of certain noncombustible by-products, particularly the steel cord commonly used in tires and slag resulting from the burning process. In recent years, significant strides have been made to provide for handling and disposal of the slag and steel by-products, such that the commercial incineration of tires as a heat source has been proven feasible in a number of industries.
The random orientation of tires as they are loaded into trucks was satisfactory for dumping at landfills. However, the commercial feasibility of burning substantial quantities of tires in furnaces has given rise to a necessity for feeding systems capable of converting a truckload of tires which are dumped in random orientation in a pile to an organized, linear alignment of tires properly oriented to facilitate fast, easy insertion into a furnace, cement kiln, or shredder in a controlled manner. A recent objective has been to develop equipment which will effect automated handling of randomly oriented tires to eliminate the labor-intensive manual handling that would otherwise be involved.
While the reorientation and transport of large quantities of articles such as food patties and the like have been addressed with various mechanized conveyor systems, many of the features are not appropriate for the handling of large, substantially toroidal objects composed primarily of elastomeric materials, as is the case with discarded tires. One approach to the automated singulation of tires from a random stack has employed the disposition of the tires in a water tank, with the use of a water wheel or other water-propelling device to direct the tires to a hook or other pick-up element that is designed to endeavor to grasp tires by the bead area and deposit the tires one at a time onto a discharge conveyor. Such a system presupposes a uniform floatation of different tires, the ability to control the displacement and orientation of the tires by movement of the water in which they are floating, and the ability of a hook to reliably grasp a tire at an appropriate time when, and if, it is positioned for pickup. To applicant's knowledge, such floatation singulation systems have not achieved widespread commercial acceptance.